Planetary anomalies ...

[DeepCut]

One of my little projects is browsing NASA archives of lunar and martian imagery for anomalies.

While browsing some Lunar Orbiter images from here :

ftp://pdsimage2.wr.usgs.gov/pub/pigp.../lunar_orbiter

(these images are in .tif format so you need a .tif viewer that can zoom, like paintshop pro or irfanview)

i suddenly had a thought about the craters.

Apparently the moon is around 5 billion years old, so one would expect heavy cratering, but one would also expect asteroids to hit the moon from all sorts of angles. And yet, practically every single crater (believe me i've spent hundreds of hours looking at these images and seen a lot of craters) leaves a nicely circular impact pattern.

This implies that all of these asteroids have hit the moon perfectly vertically, none have come in from an angle less than or more than 90 degrees to the moon's surface.

Someone must have spotted this before ? Is there a known reason, or is my common-sense at odds with my lack of astronomical knowledge ?

Any input greatly appreciated.

*** EDIT ADD ***

If anyone wants to download these images you are advised to use a proper FTP client like FileZilla :

http://filezilla-project.org/download.php

otherwise you will experience connection problems and slow downloads.

[SolFlickan]

"In an instantly classic study, Don Gault of NASA's Ames Research Center and John Wedekind of Caltech reported in 1978 that the shape of an impact crater and its ejecta pattern depend on the angle at which a projectile strikes a target. Using the Ames Vertical Gun Ballistic Range, they shot millimeter-size spheres and cylinders into targets of granite, quartz sand, and volcanic pumice powder at velocities up to 7 kilometers per second. Such experiments had already been crucial to understanding the physics of normal impact cratering, but Gault and Wedekind went one step further and asked, what happens when a projectile makes an oblique impact. Surprisingly, not much changes until the impact angle is less than 45° (measured from horizontal). But at shallower angles the crater becomes increasingly elongated in the direction of motion, and portions of the projectile ricochet and gouge out a series of small pits downrange from the main crater. As the impact angle changes, the ejecta and rays undergo even more pronounced changes than the craters do. When the impact angle is less than 15°, the ejecta pattern becomes elongated in the downrange direction and a "forbidden zone," where no ejecta appears, develops in the uprange direction. For grazing impacts of just a few degrees, the rays go sideways only, producing a butterfly-wing pattern. Amazingly, examples of all of these exotic ejecta patterns can be found on the Moon, Mars, and Venus.
Oblique impact resolves the mystery of one of the most bizarre crater pairs on the Moon. South of Mare Crisium in Mare Fecunditatis are two small craters with unique parallel rays streaming from one of them.
The unusual shapes of the craters Messier and Messier A are well seen in this CCD image by Florida amateur Maurizio Di Sciullo. North is toward the upper right.


Messier is very elongated (15 by 8 km), and the irregularly shaped Messier A (16 by 11 km) has long twin tails of rays that point away from Messier."
http://www.skyandtelescope.com/obser...n/3304151.html


Great stereo photo of Messier and Messier A here:
http://apod.nasa.gov/apod/ap091211.html



Roche V is another oblong crater on the moon:

"Roche V (38.86°S, 129.62°E) is one of five satellite craters associated with Roche crater. Compared to its siblings, Roche V is the ugly duckling of the bunch: it has an oblong, irregular shape, floor fractures, and mare fill. But, similar to the ugly duckling in the story, the geologic features that stand out and catch our attention make this 29 km diameter crater quite special indeed. The irregular shape tells us something about the crater formation, probably because the impactor hit the lunar surface at a highly oblique angle."

Go here to see LROC pic:
http://lroc.sese.asu.edu/news/?archi...g-Roche-V.html

[DeepCut]

Sol thank you very much

[SolFlickan]

Sol thank you very much

You are welcome!

[Chris]

So the Messier and Roche craters are examples of objects hitting the moon on an oblique angle. What are the odds of there being so few of these hits? Wouldn't the odds be that there are as many objects striking the moon on an angle of greater than 45 degrees as there are at less than 45 degrees?

I'm not sure what this even means to the price of tea in China!

[DeepCut]

I suppose gravity also plays it's part.

Something may approach the moon at a sharp angle but then the angle gets softened as it approaches more closely ?

[SolFlickan]

So the Messier and Roche craters are examples of objects hitting the moon on an oblique angle. What are the odds of there being so few of these hits? Wouldn't the odds be that there are as many objects striking the moon on an angle of greater than 45 degrees as there are at less than 45 degrees?

I'm not sure what this even means to the price of tea in China!

No idea what this means to the price of tea in China either.... I just anwered a question that someone posted here...

And if you look closely at moon craters there are in fact many, many of them that are not perfectly round, so impacts from a less than 45 degrees angles are not that rare.

"The Full Moon Atlas" is a good place to start if you want to go and have a look at craters for yourself and study their shapes.

http://www.lunarrepublic.com/atlas/

[DeepCut]

Nice link Sol thanks.

[rdunk]

Hi DeepCut! thanks for posting. Still a lot we don't know about the Earth, and we haven't "scratched the surface" on the moon yet, relative to REALLY knowing anything about it Or, at least we haven't been told yet! Interesting question on the moons craters!

I too have similar interests, particularly in the Mars photos. I have posted a couple of Mars anomalies here, and I have several more I will be posting. Garuda, one of the administrators, said that a forum will be set up for posting anomalies from all sources, to include the Earth, Mars, Moons, and other planets. I think it will be good to have all of that stuff in a single forum.

Garuda also suggested that, for now, we post anomalies in the "Research and Investigations" forum, until the anomaly forum was set up. These "anomaly posts" would later be moved to the new forum.

I do like the avatar - sorry one can't see the green eyes I have seen before in this pic!!!

[DeepCut]

Hi rdunk.

That's good news that we will have an anomalies area, i'm always bothering JP Skipper at marsanomalyresearch.com !

Glad you like the avatar, if only i was so pleasant on the eyes ;+}